Printing apparatuses such as printers and MFPs (digital Multi-Functional Peripherals) of recent years include an HDD (Hard Disk Drive), a large-capacity memory and the like, and these are capable of saving printing data temporarily. Since a printing apparatus is usually shared by a plurality of users most of the time, passwords are set or encryption is applied for printing data.
On the other hand, a place of using the printing apparatus is not limited to a usual office, but there is a case where it is opened to an unspecified large number of users. As an example, there are facilities such as business hotels or Net cafes. At these facilities, generally a network by a DHCP (Dynamic Host Configuration Protocol) is used. The DHCP is a protocol that is for automatically assigning information associated with TCP (Transmission Control Protocol)/IP (Internet Protocol) such as an IP address or a subnet mask for a client apparatus.
The structure of a DHCP is realized by a DHCP server that manages IP addresses uniformly, and a DHCP client to which an IP address is assigned by the DHCP server. At the DHCP server, a plurality of IP addresses are registered for the DHCP clients. On the other hand, the DHCP client is able to communicate by receiving an IP address that registered in the DHCP server at the time of startup. As described above, it is possible to save a user or a system administrator from a lot of trouble on the network by managing the information associated with TCP/IP uniformly by the DHCP server.
In the facilities such as hotels and Net cafes where the above-described DHCP network is established, the password setting or the encryption becomes further important functions since an unspecified large number of users use a printing apparatus in turns. Moreover, a so-called confidential printing that printing data is once accumulated in a printing apparatus and taken out as a printed matter by inputting a password is likely to be used as a method of using the printing apparatus from a view point of security of output results.
Here, when the unspecified large number of users use the printing apparatus one after another, the printing data once accumulated in the printing apparatus is not necessarily output immediately. For example, in a case where a user forgot to perform an output instruction of the printing data and left as it is after a printing instruction and left the facility, the printing data that is not output is left without being deleted, thus resulting in a problem of shortage of free space of a storage apparatus in the printing apparatus before long.
For such a problem, for example, Japanese Laid-Open Patent Publication No. 2008-5092 describes an image forming apparatus that is capable of deleting printing data which has elapsed a certain period of time from an external storage apparatus. The image forming apparatus includes a function of automatically deleting the file corresponding to an elapse of saving period of a file stored in the external storage apparatus.
However, in the image forming apparatus described in the above Japanese Laid-Open Patent Publication No. 2008-5092, a problem such as following occurs. That is, since the staying time of a user varies at a hotel, Net cafe and the like, it is difficult to set a certain saving period for the image forming apparatus. Moreover, although a method of prompting a user to set a saving period may be considered, in this case, the user is forced to be burdened with a setting operation, thus some users may not perform the setting. Therefore, it is difficult to set a saving period of a file for each user.